John Deere 000158.03 – CAB: High Ignition Supply Detected

The Cab Control Unit (CAB) is receiving a voltage level on its switched power supply circuit that is above the manufacturer's specified maximum threshold. The system expects a certain voltage when the ignition is on, and this fault is triggered when the actual voltage significantly exceeds that expectation. This is a general high voltage condition affecting the entire Cab Control Unit, which manages multiple functions including climate controls.

• 7000 Series
• 8000 Series
• 9000 Series
• 7030 Series
• 8030 Series
• 8130
• 8230
• 8330
• 8430
• 8530
• 9030 Series
• 9230
• 9330
• 9430
• 9530
• 9630
• R Series
• T Series

1. 1

   Restart the engine to see if the fault code is intermittent and clears on its own

2. 2

   Visually inspect the battery terminals and alternator cables to ensure they are clean, tight, and free from corrosion or debris

3. 3

   Check the cab power supply lead (the secondary 'piggyback' wire on the main positive battery cable) at the battery terminal to ensure it is secure and not corroded

4. 4

   Inspect the main cab fuses (maxi-fuses) and fuse panel for signs of corrosion on the fuse holders or the fuses themselves

5. 5

   Examine the wiring harnesses leading to the Cab Control Unit, particularly where they pass through the frame or under the operator's seat and dash, for signs of damage from rubbing, pinching, or rodents

1. 1

   Correct connection issues

   Clean and tighten any loose or corroded connections found during the diagnostic checks. Replace any damaged battery cable ends or fuse holders.

2. 2

   Test alternator output

   Use a multimeter to test the alternator's voltage output. An over-charging condition caused by a faulty voltage regulator within the alternator can trigger this high-voltage fault code.

3. 3

   Repair wiring harness

   If damaged wires are found, repair them by splicing, soldering, and sealing with heat-shrink tubing to ensure a durable and weather-resistant connection.

4. 4

   Perform dealer diagnostics

   If simple checks and repairs do not clear the code, the issue may be with the Cab Control Unit itself. Have a John Deere dealer perform further diagnostics using Service Advisor software.